The Section on Brain Aging and Dementia, located in Bethesda, is studying brain function and metabolism in healthy men at different ages, and in patients with Alzheimer's disease and autism. Brain glucose utilization in specific regions was measured by positron emission tomography (PET) scanning and 18-Fluorodeoxy-glucose. Statistically significant declines in glucose utilization did not occur in men between 21 and 83 years, indicating that oxidative metabolism remains normal in the healthy elderly, under resting conditions and in the absence of disease. Psychometric evaluation showed age-related decline in memory but not in parameters of crystallized intelligence (verbal ability). Reaction time increased with age. Overall motor activity, as measured with a patient activity monitor, fell with age. An outpatient dementia clinic was established for evaluation and screening of subjects with various types of dementia.